A surprisingly complex concept, although central to any account of human and animal motivation. Perhaps the simplest theory of pleasure treats it as being on the same dimension as pain: a bodily sensation, but of a positive kind, where pain is of a negative kind. This, however, fails to account for cases where we take pleasure in an activity or from receiving a piece of news, when nothing like a pleasurable taste or other sensation is apparent. As Aristotle pointed out, we cannot say that the pleasure we take in an activity is a kind of sensation that could in principle have been obtained by some other activity: rather, the pleasure forms a complement of the activity ‘as bloom in the case of youth’ (Nicomachean Ethics, x. 4). Furthermore, it seems contingent whether any sensation is pleasurable or otherwise, depending upon other desires and concerns. Pleasure seems more to be a quality of consciousness, intimately connected to contentment or happiness, rather than another element within conscious experience. Pleasure has often been proposed as the end of all action, either because this is what actually motivates us, or because there is a concealed contradiction in the idea of action that is not so motivated (see hedonism). The ideal of much economic and social philosophy would be to measure pleasures, with the object of constructing a felicific calculus for use in social choice theory. But pleasure proves remarkably resistant to such a treatment. Whilst we can make crude comparative judgements (this year's holiday gave us more pleasure than last year's, when it rained), the subject seems inherently resistant to quantitative treatments. Questions such as whether one gets more pleasure from art or music, leisure or work, seem to become rapidly meaningless. See also Epicureanism, hedonism, measurement, utility.